There’s a reason we rarely see photographs of people in swimming pools with huge frowns on their faces: namely, because jumping into — or lolling about in, or just hanging out beside — a pool on a sunny day is one of life’s enduring pleasures. The reasons we’re drawn to swimming pools, meanwhile, are as varied as the types, shapes and sizes of pools that designers and engineers have devised over the years. Some of us visit the pool for exercise; some of us, of course, are invariably poolside to see and be seen; many of us quite simply love, with a near-primal fondness, the feel of being in the water. In the end, it’s elemental: pools are cool.

Here, as summer truly kicks into gear and countless humans around the world make their way to hotel pools, backyard pools, public pools, sunken pools, above-ground pools and wading pools, TIME.com celebrates this most basic — and playful — of urges with a series of photos featuring movie stars (Sophia Loren, Gina Lollobrigida), rock and rollers (the Beatles), at least one political heavyweight (Robert Kennedy) and a number of other figures, both well-known and wholly anonymous, with nothing on their minds for the moment but making a splash.